<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>案例3</title>
		<style type="text/css">
		#div1{
			width: 800px;
			height: 80px;
			background-color: red;
			}
			#div2{
				width: 800px;
				height: 80px;
				background-color: red;
				}
				#div3{
					width: 800px;
					height: 80px;
					background-color: red;
					}
					#div4{
						width: 500px;
						height: 40px;
						background-color: green;
						}
						#div5{
							width: 500px;
							height: 40px;
							background-color: #000000;
							}
							#div6{
								width: 500px;
								height: 40px;
								background-color: black;
								}
			</style>
	</head>
	<body>
		<div id="div1"></div>
		<div id="div2"></div>
		<div id="div3"></div>
		<div id="div4"></div>
		<div id="div5"></div>
		<div id="div6"></div>
	</body>
</html>
